The invention concerns a very large telescope for the observation of luminous phenomena in the visual, near ultraviolet and infrared spectral regions by means of a primary reflector, comprising several individual reflectors, a secondary reflector mounted in front of the primary reflector and a supporting structure including a yoke for the primary reflector and an auxiliary structure which holds the secondary reflector.
The instrument can as well be used for emitting high energy pulses.
Individual reflectors for the spectral domain of about 0.3 to 30 (or even 300) .mu.m are subject to a natural limit of the diameter at about 5 to 7 meters due to the difficulties of fabrication, polishing, transport and handling. Although the manufacturing of larger monolith mirrors seems possible in principle, this is not proposed here considering the costs. There is, however, a demand for optical telescopes with diameters of 7 meters or more.
It has been tried to transgress this limit by composing the primary reflector of a very large optical telescope of a mosaic of many individual reflectors which can be manufactured in the usual way, and later on composed on a substructure to a single primary reflector. This proposal was at least made and published in 1984 by Meinel et al., Very Large Telescopes, their Instrumentation and Programs, International Astron. Union Colloq. No. 79 (Eds.: M. H. Ulrich, K. Kjar, Garching 1984, page 109). In this publication the construction of an extremely stiff and accurate substructure is proposed, providing support points for the relatively weak individual reflectors held by vacuum.
In such a concept of an optical large telescope the functions of support and of reflection are separated, but it is doubtful whether its advantage can be realized. The exact grinding of the support point structure requires extremely accurate machinery of the size of the primary reflector which could be very expensive. A further difficulty is the testing of the mosaic mirror. The adjustment, and testing requires a very accurate null-test mirror for the formation of a reference wave front which in this size is not available at present.